I live near St Petersburg FL. Options really run the gamut. There are a few yacht and country club setups like Ted mentions that I've never been in ("I wouldn't join a club that would have me as a member"), and marinas are fairly plentiful, most have condos nearby but not affiliated. Many condos have marinas as part of their association. Condo marinas come in two broad flavors. First is you rent a slip from the condo association. Second is some form of ownership where you actually own the slip. These arrangements run the gamut from high end condos down to old funky arrangements. Finally, there are a Lot of houses on water where people have their boat in their backyard.
A lot depends on what size boat you're thinking of. 25-foot center console boats are extremely popular and many of the slips are setup for lifts. Obviously not the liveaboard you're talking about, but if you're thinking of a 60-footer, chances are you will need to find a marina that happens to have a condo nearby or the yacht/country club gig.
A friend moved to Florida about 6-years ago with an idea to liveaboard his 60-foot power cat. Marinas to handle that were few and slip rent around $2000/mo. He decided to buy a house on an open canal and put his boat there. Cost at the time was around $700k, but now is worth about $1.25m. Values are crazy right now. But still, if he wanted to head out cruising, he could easily rent his house for $5k-$6k per month.
Personally, I went the low budget route of finding a deeded slip on the ICW that happened to come with an old 1950s era efficiency condo. I rent the condo vrbo which covers the costs. It was affordable 10-years ago when I bought it. With Florida real estate, not so sure these days.
BTW - I moved from SF to Florida in 2005. No regrets.
Peter